The hollow cathode discharge is studied as a new type of ionization source for trace element analysis by mass spectrometry. A simplified instrumental system is being developed by combining the hollow cathode discharge with a quadrupole mass filter. Use of argon as a discharge gas allows sputter atomization-ionization of metal samples directly or of solution residue samples deposited on the cathode surface. The instrument will be evaluated by studying analytical results from NBS standard biological samples, such as orchard leaves and bovine liver.